Display case for frozen food



March 12, 1957 J. A. CANTER 2,784,564

DISPLAY CASE FOR FROZEN Foon Filed Feb. 21, 1956 35 I5 i I,

UUU UB 46 32 3 000000 IN V EN TOR.

James A. Canter. BY

His Attorney" United States Patent DISPLAY CASE FOR FROZEN FOOD James A.Canter, Dayton, Ohio, assignor to General Motors Corporation, Detroit,Mich., a corporation of Delaware Application February 21, 1956, SerialNo. 566,863

8 Claims. (Cl. 62--89.6)

This invention relates to refrigerated display cases and particularly toopen top cases of the reach-in selfservice type.

In open top display cabinets or cases wherein a sufficient amount ofcold air is circulated over a food storage compartment to preserve foodproducts therein at a below freezing temperature and preferably aroundF. it is necessary to maintain a blanket of air thereover of uniformthickness. This has heretofore been a problem because the formation ofeddy currents in the stream of air circulated over the compartment couldnot be prevented. Such is particularly true when the food load in thecompartment is raised to a point closely adjacent the top of an open topcompartment so as to render the food packages therein readily accessiblewithout requiring undue stooping or bending on the part of customers.Eddy currents in the stream of air over an open top compartment set upturbulences in the blanket of air and this thins the blanket at certainpoints above the foods thus causing warm spots in the compartment belowthe cabinet open top. I have found that the eddy currents are to a greatextent formed or set up in a blanket or stream of air circulated over anopen top compartment of a reach-in or self-serve display case by air ofthe blanket or stream escaping entrance into the inlet opening of an airreturn duct as the air of the stream approaches this opening. Theescaping airstrikes a part of the cabinet and rises above the stream ofair where, upon comingling with air ambient to the cabinet, it has itsdirection of flow reversed and swirls around on top of and in contactwith the upper part of the air blanket or stream circulating over foodsin the open top.

food storage compartment. This swirling air creates a turbulence of airabove the blanket or stream thereof and causes, even when none isreaching into the compartment, formation of eddy currents in the blanketor stream of air. In addition to thinning the blanket of air over thetop of the compartment the escaping air causes warmer make-up airambient to the cabinet to enter the stream which augments the formationof eddy currents therein. My invention is specifically directed tominimizing the formation of eddy currents ina blanket or stream of aircirculating over an open top food compartment of a display case wherebyto maintain a uniform thickness thereof across the compartment and toreduce to a minimum entrance of air from above the open top of the caseinto the exposed air blanket or stream.

An object of my invention is to retard or prevent as faras possible,escape of cold circulating air in an open top display case from the casein order to maintain stored foods therein at a uniform low temperatureand to improve the etficiency of refrigerating apparatus associated withthe case.

Another object of my invention is to provide means in or on an open toprefrigerated display case which will reduce or substantially eliminateswirling and co- "mingling of air escaping entrance into. the inlet of areturn air duct or flue in the case above an air stream circulating.over a food storage compartment therein.

A further object of my invention is to momentarily trap a substantialamount of air which escapes from a cold stream thereof circulated overthe top of a food compartment upon approaching the inlet of an airreturn flue in an open top display case and to continually release someof the trapped air to the air stream for entrance into the return flue.

A still further and more specific object of my invention is to providean open bottomed pocket or turbulence chamber in front of and above theinlet to a return air flue for a stream of air in an open toprefrigerated display case wherein air escaping the return flue inletwill be momentarily trapped against outward flow from the case, ispermitted to swirl in the turbulence chamber and will eventually reenterthe stream and flow therewith into the flue.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred form of the present invention is clearlyshown.

In the drawings:

Figure 1 is a perspective view of a horizontally elongated refrigerateddisplay case having my invention embodied therein;

Figure 2 is a vertical sectional view taken on the line 22 of Figure 1through the open top display case cabinet showing the essential featuresof the invention; and

Figure 3 is a fragmentary sectional view similar to Figure 2 showing howair swirls at the top of a conventional display case devoid of theimprovement herein disclosed.

In the drawing 10 generally designates an open top display case orcabinet having insulated end walls 20 (see Figure 1), an insulatedbottom wall 11 (see Figure 2), an insulated upright front wall 12including a multiple pane glass upper part or section 13, an insulatedupright back wall 14 and an insulated hood 15 extending forwardly overback wall 14 a short distance. Suitable metal plates or sheets aresecured together and spaced by brackets or the like from the liner ofwalls 11, 12, 13 and 14 (see Figure 2) to form an impervious bottom wall16, an upright front wall 17 and. a rear wall 18 of an open top frozenfood storage compartment 19 within the cabinet 1%). The walls 16, 17 and18 also provide an air passage 21 below compartment 19, and an uprightfront air feeder flue 22 and an upright back return air fine 23respectively within cabinet 10. A single glass plate 24, spaced from themultiple pane glass section 13, forms the upper portion of the frontwall of compartment 19 and the top wall part of flue 22. An upstandingcontinuation of wall 18 is formed to provide a shroud 26 in the hood 15for a purpose to be presently described. An insulated horizontallyanchored partition 25 is spaced from and cooperates with the dependingend of the insulated forward portion of hood 15 to provide an inlet 27for the return air fine 23. The vertically spaced apart means, partition25 and the end of the depending insulated forward portion of hood 15,extends through the length of the cabinet. Splitter means in the form ofa lip 31, extending inwardly of the case from the front glass section13, and spaced preferably transparent bafiles 32 oifset slightlyrelative to one another secured beneath lip 31 split or divide ,a streamof air egressing from the upper outlet end of feeder flue 22 into aplurality of layers for and in the manner to be hereinafter explained. Imount an evaporator 33 of a refrigerating system within the space 34 ofhood 15 be low the shroud 26 and a motor 36 and fan 37 above the space34. The shroud 26 surrounds fan 37 and creates a: suction therein topull air upwardly through space 34 over and around evaporator 33.Evaporator 33 is connected by a conduit 41 to a sealed motor-compressorenclosing casing 42 of a refrigerant translating unit which alsoincludes a condenser 43. Condenser 43 receives compressed refrigerantfrom the compressor in casing 42 wherein it is cooled and liquified.Liquid refrigerant is directed to evaporator 33 through a conduit 44 andits entrance into the evaporator may be controlled by an expansion valveor the like (not shown). Operation of the motor and compressor of therefrigerating system may be under the control of a thermostaticallyactuated switch as is conventional in the art.

According to my invention I provide an open bottomed pocket orturbulence chamber in front of theinlet openingof the return air flue.atthe backof the present display casefor a purpose to become apparenthereinafter. A member preferably of molded plastic translucent materialincluding .Wall partitions 45, 46 and 47 extends along the length .ofthezinlet 27 of the back return air flue23 in cabinetlfi'in front andabove this in let. Wall portion 47 of the translucent member isremovably locked to the front parto'f hood 15 by spring clips or thelikewiththe end of wall portion dfibearing'against the hood. Wall portions46 and 47 of the molded plastic-member close'the lowerzportion of a lampcompartmentdsat the front of hood 15 in which is suitably mounted anilluminating lamp bulb 49. Wall portions45 and 46 of the translucentmember cooperate with one another and with the front of hood 15 to formor provide an open bottomed air turbulence chamber or pocket '50.Suction in the shroud '26 and chamber 34, created .by operation of motor36 and fan 37, draws air into the inlet openmg 27 upwardly through andover the evaporator 33, Which cools the air to a temperature well below32 F., and forces the air downwardly in the back return flue 23. Thecool air is circulated forwardly from flue 23 across the passage 21 andupwardly in the feeder flue 22 to cool thewal ls '16, 17 and 18 andconsequently packaged food, such as ice cream, contained in compartment19. The alr stream egressing from the outlet of feeder flue Z2 is at atemperature of approximately -l F. and is stratified or divided into aplurality of superimposed streams or layers and directed at differentvelocities with respect to one another horizontally rearward over theopen top of compartment 19 by the splitters or bafiles 32 Thearrangement of splitters 32 is such that they will deflect a fast movinglayer of air, a slower moving layer of air thereabove and a still slowermoving layer of air from the bottom to top respectively of the blanketor stream of air flowing over the open top of compartment 19. As air inthe blanket or plural layer stream approaches or nears the inlet opening27 of back return flue 23 some of the air in the slower moving upperlayer or strata of the stream becomes slightly warmed due to itsexposure to air above the open top of compartment 19 and due to anadditional amount of air induced into motion by the stream above thatwhich is circulated by the fan'or fans. This warmer air, relative to thetemperature of the lower layers or strata thereof, has a tendency torise and escape entrance into the inlet 27. This is an inherentcharacteristic in open top display cases oc curring regardless of therelative height of inlet and outlet openings of air flues therein. Insuch cases where the air is circulated over a compartment toward theforward side thereof the top of the case front wall must be disposed aconsiderable distance above a forward flue inlet and the top of the foodload or air escaping entrance to the flue inlet will flow over its frontwall and all the escaping air will be lost to air ambient to the case.Thus if a front wall of a display case is elevated above the food loadsufficiently to stop air tending to escape a' front flue inlet thefeature of locating the top of the food load closelyadjacent the opentop of a display case will be defeated. Substantially all or the.greater portion of the rising or escaping air is, in the presentdisclosure, caught;

and trapped in the open bottomed turbulence chamber or pocket 50 andswirls therein. The swirling air looses its kinetic energy in chamber 50and as more escaping air is caught in this chamber some of the trappedair swirling therein reenters the stream of rearwardly circulating airand flows therewith into the inlet. This process continues and in doingso the warmed air escaping entrance into the inlet 27 is prevented fromflowing forwardly of hood 15, comingling with air above the blanket orstream circulating across the open top of compartment 19 and creating aswirling action of air along the length of the exposed air stream. Inother words swirling of air'escapingentrance into theinlet 27 of thereturn air fiue 23 is-confined, by the turbulence chamber 50, in aregion where it will do little harm and is prevented from spreadingforwardly over the major portion of the blanket or stream of air abovethe open top compartment 19. In this manner the formation orestablishment of eddy current in the circulatingblanket or stream of airover the food compartment is substantially eliminated so as'not toretard movement of the blanket or stream. This results in themaintenance of a more uniform thickness of the blanket or stream ofaircircu- 'lating over compartment 19. By trapping air escaping entranceinto inlet 27 and eliminating theformation of .a wide spread turbulenceor swirling of air above the circulating exposed stream thereof lessmakeup air enters cabinet or case 10 and a lower temperature of foodsadjacent the open top of display case or cabinet is obtained.

In order to emphasize comparison of the present improvement with or overconventional open top display cases or cabinets I show in Figure 3 ofthe drawings a display case of a construction similar to that disclosedin Figures 1 and 2 devoid of my improvement and illustrating theextended zone of harmful swirling action of air above the blanket orstream of cold air being circulated over the open top food compartment.The arrows 51 indicate the extended swirling or turbulence of air whichescapes entrance into the inlet 27 of the return air flue. It should benoted that the turbulence of air above the exposed air stream extendssubstantially to the front of the open top compartment 19. Theretardation inmovement of the blanket or stream of air by eddy currentsestablished therein by the swirling air is indicated in Figure 3 by thedotted lines 52. This comparison is realistic and actual tests haveshown that, with the addition of my improvement to a conventional opentop display case, a lower temperature of packaged ice cream in the upperportion of compartment of from 10 to 15 F. is had by my invention overthat obtained in a conventional case under the same operating andambient conditions.

Since packaged foods stored in the upper portion of compartment 19aremore diflicult to cool to a low uniform temperature than packagedfoods elsewhere in compartment 19, my invention is particularlybeneficial to this characteristic of open top display cases.

From the foregoing it should be apparent that my improvement permits theflow of a fast unretarded, uniform thickness of a blanket or stream ofcold air over food stored in an open top compartment of a substantiallyopen top display case to thereby more efiiciently and uniformlyrefrigerate foods stored therein to a below freezing temperature. Thefront wall portion of the molded plastic translucent member, forming theturbulence chamber in the present disclosure, may serve as a display oradvertising space to inform customers of the various kinds or flavors ofice cream stored in the cabinet. For example, this wall portion of theplastic member may have indicia printed or painted on the front thereofand made readily visible at the forward side of the case by beingilluminated by the lamp in the lamp compartment above the turbulencechamber. Thus the molded plastic member serves a two-fold-purpose for anopen top display case.

:While the form of embodiment of the invention as-herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adapted, as may come within the scope of the claims whichfollow.

What is claimed is as follows:

1. In a refrigerated display case, an elongated substantially open topcabinet provided with a compartment having an air passage therebelow, areturn air flue at one side thereof with its inlet near the top of saidcom partment and a feeder flue at the side of said compartment oppositesaid return flue with its outlet also near the top of the compartment,means for circulating air downwardly in said return flue through theinlet thereof, across said passage, upwardly in said feeder flue and outof the outlet thereof in a stream over the top of said compartment inexposed relationship to air at the open top of said cabinet, and meansfor cooling the circulating air, the improvement which comprises theprovision of a turbulence chamber along the length of said compartmentin front of and above the inlet of said return flue, said chamber beingopen at its bottom to receive and momentarily trap air which escapesfrom said stream thereof upon approaching the inlet of said return fluewhereby said trapped air swirls in said chamber, and the swirlingtrapped air causing 'some of it to reenter air in said stream adjacentsaid inlet of the return flue and flow therewith into said return flueto minimize entrance of air from above the open top of said cabinet intosaid air stream.

2. In a refrigerated display case, an elongated substantially open topcabinet provided with a compartment having an air passage therebelow, areturn air flue at the back thereof with its inlet adjacent the top ofsaid compartment and a feeder flue at the front of said compartment withits outlet also adjacent the top of the com partment in substantiallythe same horizontal plane with the inlet of said return flue, means forcirculating air downwardly in said back return flue through the inletthereof, forwardly across the case through said passage, upwardly insaid front feeder flue and out of the outlet thereof in a stream towardthe rear of the case over the top of said compartment in exposedrelationship to air .at the open top of said cabinet, and means forcooling the circulating air, the improvement which comprises locating anopen bottomed pocket along the length of said compartment in front ofand above the inlet of said back return flue, said pocket serving toreceive and momentarily trap air which escapes from said stream thereofupon approaching the inlet of said return flue for decreasing flow ofthe escaping air into the region above the stream of air circulatingover said compartment whereby to minimize the formation of eddy currentsin said stream of air.

3. In a refrigerated display case, an elongated substantially open topcabinet provided with a compartment having an air passage therebelow, areturn air flue at the back thereof with its inlet adjacent the top ofsaid compartment and a feeder flue at the front of said compartment withits outlet also adjacent the top of the compartment in substantially thesame horizontal plane with the inlet of said return flue, means forcirculating air downwardly in said back return flue through the inletthereof, forwardly across the case through said passage, upwardly insaid front feeder flue and out of the outlet thereof in a stream towardthe rear of the case over the top of said compartment in exposedrelationship to air at the open top of said cabinet, and means forcooling the circulating air, the improvement which comprises theprovision of a turbulence chamber along the length of said compartmentin front of and above the inlet of said back return flue, said chamberbeing open at its bottom to receive and momentarily trap air whichescapes from said stream thereof upon approaching the inlet of saidreturn flue whereby said trapped air swirls in said chamber, and theswirling trapped air causing some of it to reenter air in said streamadjacent said inlet of the returnflu'e and flow therewith into saidreturn flue to minimize entrance of air from above the open top of saidcabinet into said air stream.

4. In a refrigerated display case, an elongated substantially open topcabinet provided with a compartment having an impervious bottom formingthe top of an air passage therebelow, a return air flue at one sidethereof with its inlet near the top of said compartment and a feederflue at the side of said compartment opposite said return flue with itsoutlet also near the top of the compartment, means for circulating airdownwardly in said return flue through the inlet thereof, across saidpassage, upwardly in said feeder flue and out of the outlet thereof in astream over thetop-of said compartment in exposed relationship to air atthe open top of said cabinet, means for cooling the circulating air, andsplitter means at the outlet of said feeder flue for stratifying airegressing therefrom into a plurality of layers of different velocitywith a faster moving layer underlying a slower moving layer and fordirecting said stratified stream of air toward the inlet of said returnflue, the improvement which comprises locating an open bottomed pocketalong the length of said compartment forwardly of and above the inlet ofsaid return flue, said pocket serving to receive and momentarily trapair which escapes from an upper slower layer thereof in said stratifiedstream upon approaching the inlet of said return flue for decreasingflow of the escaping air into the region above the stratified stream ofair circulating over said compartment whereby to minimize formation ofeddy currents in said stream of air.

5. In a refrigerated display case, an elongated substantially open topcabinet provided. with a compartment having an impervious bottom formingthe top of an air passage therebelow, a return air flue at one sidethereof, with its inlet near the top of said compartment and a feederflue at the side of said compartment opposite said return flue with itsoutlet also near the top of the compartment, means for circulating airdownwardly in said return flue through the inlet thereof, across saidpassage, upwardly in said feeder flue and out of the outlet thereof in astream over the top of said compartment in exposed relationship to airat the open top of said cabinet, means for cooling the circulating air,and splitter means at the outlet of said feeder flue for stratifying airegressing therefrom into a plurality of layers of different velocitywith a faster moving layer underlying a slower moving layer and fordirecting said stratified stream of air toward the inlet of said returnflue, the improvement which comprises the provision of a turbulencechamber along the length of said compartment forwardly of and above theinlet of said return flue, said chamber being open at its bottom toreceive and momentarily trap air which escapes from an upper slowerlayer thereof in said stratified stream upon approaching the inlet ofsaid return flue for decreasing flow of the escaping air into the regionabove the stratified stream of air circulating over said compartmentwhereby to minimize entrance of air from above the open top of saidcabinet into said air stream.

6. In a refrigerated display case, a substantially open top cabinetprovided with a compartment having an impervious bottom forming the topof an air passage therebelow, a return air-flue at the back thereof withits inlet adjacent the top of said compartment and a feeder flue at thefront of said compartment with its outlet also adjacent the top of thecompartment in substantially the same horizontal plane with the inlet ofsaid return flue, means for circulating air downwardly in said backreturn flue through the inlet thereof, forwardly across the case throughsaid passage, upwardly in said front feeder flue and out of the outletthereof in a stream over the top of said compartment in exposedrelationship to air at the open top of said cabinet, means for coolingthe circulating air, and splitter means at the outlet of said feederflue for stratifying air egressing therefrom into aplurality oflayers ofdifferentvelocity with a faster moving l'ayer underlyinga slower movinglayer and for directing said Stratified stream of air rearwardly of thecase toward the inlet of said return flue, the improvement whichcomprises locating an open bottomed pocket along tthe length :of saidcompartment in front of and above the inletof'said back return flue,said pocket serving to receive and momentarily trap. air which escapesfrom an upper slower layer thereof in said stratifi'ed stream uponapproaching the inlet of said return flue for decreasingflow of'theescaping-air into the region above the stratified stream of aircirculating over said compartment whereby to minimize formation of eddyvcurrents in said stream of air.

7. In a refrigerated display case, a substantially open top cabinetprovided with a compartment having an impervious bottom forming the top.of an air passage therebelow, a'return air flue at the back thereof withits inlet adjacent the topof said cornpartment and a feeder flue at thefront of said compartment with its outlet also adjacent the top of thecompartment insubstantially the same horizontal plane with the inlet ofsaid return flue, meanstfor circulating air downwardly in said backreturn flue through the inlet'thereof, forwardly across the case throughsaid passage, upwardly insaid front feeder fiue and .out of the outletthereof inna stream over the top of saidcompartment in exposedrelationship to air at the open top of said cabinet, means for coolingthe circulating air, and splitter means atithe outlet of said feederflue'for stratifying air egressing therefrom into a plurality of layersof different velocity with a faster moving layer underlying a slowermoving; layer and for directing said Stratified stream of air rearwardlyof the case toward the inlet vof said return flue, the improvement whichcomprises the prov-ision of a turbulence chamber along the length ofsaid compartment forwardly of and above the inlet of said back returnflue, said chamber being open at it-szbottom to receive and momentarilytrap air which escapes f'roman upper slower layer thereof in said'astrati fied stream upon approaching the inlet of said back return fluewhereby said trappedair swirls in said'chamber, and the swirling trappedairica'using some-of it to reenter air in said stream adjacent saidinlet of the return flue and flow'therewilthinto said back returnfiue tominimize entrance of :air from above the open top of said cabinet intosaid stratified' air stream.

8. In. a refrigerated display case, a substantially open top cabinethaving, a frozen food storage compartment therein provided with apassage therebelow, a return air flue at one side thereof and a feederflue at the side of said compartment opposite said return flue with itsoutlet near the-top-of the compartment, vertically spaced apart meansnear the top of said compartment providing said return flue with aninlet, means for circulating air downwardly in said return flue throughthe inlet thereof, across said passage, upwardly in said feeder 'flueand out of the outlet thereof in a stream over the top of saidcompartment in exposed relationship toair at the open top of saidcabinet, and means for cooling, the circulating air to a temperaturewell below 32 F-., the improvement which comprises the provision of aturbulence chamber along the length of said compartment in front of saidvertically spaced apart means above the inlet of said return flue, saidchamber being open at its bottom to receive and momentarily trap airwhich escapes from said stream thereof upon approaching the inlet ofsaid return flue whereby said trapped air swirls in said chamber, andthe swirling trapped air causing some of it to reenter air in saidstream adjacent said-vertically spaced apart means and flow therewithinto the inlet of said return flue to minimize entrance of air fromabove the open top of said cabinet into said air stream.

References Cited in the file of this patent UNITED STATES PATENTS2,715,321: Burger Aug 16, 1955

